Automotive brake testing machine



Aug. 3, 1943. HETZEL 2,325,910

AUTOMOTIVE BRAKE TESTING MAdI-IINE Filed Oct. 1, 1941 2 Sheets-Sheet l 7J3 H F 1N VENT OR:

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AT TOEWEK Aug. 3, 1943. F. L. HETZEL AUTOMOTIVE BRAKE TESTING lvmnmEFiled Oct. 1, 1941 2. SheetS-Sheet 2 1N VENTOR:

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W 1' ATTORNEY,

Patented Aug. 3, 1943 zyzgrg r 2,325,910 AuTor/ro'rrva BRAKE TESTINGMACHINE Frank L. Hetzel, Hermosa Beach, Calif.

Appiication October 1, 1941, Serial No. 413,172

3 Claims.

This invention relates to mac'hines for testing automotive brakes, andthe general object of the invention is to provide an improved automotivebrake-testing machine, which will record the number of feet within whicha motor vehicle may be stopped by its brakes'while traveling at a givenspeed.

A more particular object is to provide an automotive brake-testingmachine of the character stated which will be simple, inexpensive andaccurate and efficient in operation.

Other objects and advantages will appear hereinafter.

The invention is illustrated in the annexed drawings which form a partof this specification and in which:

Fig. 1 is a side elevation of my invention attached to an automobile fortesting the brakes of the automobile.

Fig. 2 is a plan view of my invention on an enlarged scale.

Fig. 3 is a side elevation of my invention on an enlarged scale.

Fig. 4 is a diagram of the electric circuit which controls the operationof my invention.

Fig. 5 is a vertical longitudinal section of my invention taken on line5-5 of Fig. 2.

Fig. 6 is a transverse vertical section of my invention taken on line6-6 of Fig. 2, with gear I! omitted. I

Fig. 7 is a vertical section taken on line 1--1 of Fig. 2 showing thespeedometer and its operating means of my invention.

Fig. 8 is a side view of the switch of the controlling circuit of myinvention and the brake pedal of an automobile to which said switch isattached.

Fig. 9 is a vertical section of a modification of the speedometer brake.

Referring more particularly to the drawings, in which correspondingparts are designated by the same reference characters in all of thefigures, my invention embodies a trailer I, comprising a body 2, an axle3, wheels 8 on the ends of said axle, and a tongue 5 extending forwardlyfrom said body. The axle 3 is journaled in bearings 6 in the side wallsof the body 2. A clamp 1 is connected to the forward end of the tongue 5by a universal joint 8, which clamp is constructed and arranged to clampon the rear bumper 9 or any suitable part of a motor vehicle l0, and hasa clamp screw H for securing the clamp to said bumper. Said universaljoint 8 permits the trailer I to turn and move up or down with rela tionto the automobile to which the trailer is connected.

On the trailer l is mounted distance measuring meter l2 and aspeedometer l3.

The distance-measuring meter I2 includes a dial M, a dial indicator arm15, an indicator shaft l6 carrying on its upper end, said indicator arm,a worm wheel ll secured on the lower end of said indicator shaft I6, aworm [8 in mesh with said worm wheel, a shaft H! on which said worm issecured, a gear 20 secured on said shaft and a pinion 2| secured on theaxle 3 of the trailer I in mesh with said gear 20. The dial I4 issecured upon a plate 22 which is secured upon the upper wall 23 of thebody 2 of the trailer I and said dial is divided by a series of radialgraduations 26 indicating feet and inches, from 1 to feet, to whichgraduations the indicator arm l5 points to indicate the number of feetand inches a motor vehicle travels from the time the brakes of thevehicle are put on or applied until the vehicle stops, as will behereinafter more fully described. The indicator shaft [6 is journaled ina bearing 25 depending from the upper wall 23 of the body 2 into saidbody 2. The ends of the shaft H] are journaled in removable bearings 26detachably secured to the side walls of th body 2 by screws 26. Theindicator shaft [5 is formed at its upper end with an external annularflange 21 and a threaded stud 28 upstanding from said flange, axially ofsaid shaft, on which stud is turnably fitted the inner end of theindicator arm l5, which is provided with an opening 29, through whichsaid stud loosely extends. On said stud 28 is fitted a washer 30 oversaid indicator arm l5 and a nut 3| is threaded on the upper end of saidstud against said washer, whereby the inner end of the indicator arm i5is clamped on the stud 28 between the flange 21 and the washer 30. Saidindicator arm i 5 is clamped between said flange 27 and said washer 30by said nut 3| with sufficient friction to cause said indicator arm tobe turned with the indicator shaft 16, except when said arm is engagedby a stop 32, which overcomes said friction and holds said armstationary, pointing to the zero graduation 24, while the shaft l6rotates with its stud 28 turning in said arm and the flange 2'! andWasher 38 turning ainst said arm. The stop 32 may be in the form of asolenoid 33, with its coil 34 mounted in the body 2, and its core 35 inthe form of a pin extending upwardly through the upper wall of said body2 and the dial Hi, adjacent the inner end and at the left side of thezero graduation 26, there being a flange 36 on said core and a coilspring 31 surrounding said core between said coil 34 and said flange 36,which spring normally holds said core projected upwardly in the positionaforesaid for arresting the indicator arm in its zero position as shownin Figs. 2 and 5.

The speedometer l3 includes a casing 40, a dial 4| in the upper part ofsaid casing, an indi cator arm 42 above said dial, an indicator shaft43, on the upper end of which is secured said indicator arm, a soft irondisk 44 secured on said indicator shaft between its upper and lowerends, a return spring 45 coiled around said indicator shaft 43, betweensaid dial 4| and said iron disk 44, and secured at its ends to said dialand said disk respectively, a permanent magnet disk 46, a drive shaft41, on the upper end of which said magnet disk is secured directly undersaid soft iron disk 44, a bevel pinion 48 secured on the lower end ofsaid drive shaft, and an externallythreaded bearing 49 depending fromthe lower wall of said casing 49 in which bearing said drive shaft 41 isjournaled. Said drive shaft 41 extends downwardly from within saidcasing through said bearing 49 and the lower portion 59 of saidindicator shaft 43 is reduced in diameter and is journaled axially insaid magnet disk 46 and in the upper end of said drive shaft 41, whilethe upper end of said indicator shaft 43 extends through the dial 4| andis journaled therein. The dial 4| is marked with graduations 5| from 1to 100 to which the indicator arm 42 points, to indicate the miles perhour that the motor vehicle, to which the trailer I is attached,travels. The upper wall 52 of the casing 49 is glass, through which themiles per hour lndicated by the indicator arm 42 and the graduw tions 5|may be read. The casing 40 i mounted on the plate 22 which extendsbeyond one side of the casing 2, said plate being provided with anopening 53 through which the bearing 49 of said casing depends. To thelower side of the plate 22 is secured an internally-threaded coupling 54in axial alignment with the opening 53 in said plate. An inverted yoke55 is formed with an upstanding coupling stud 56 which is externallythreaded for threaded engagement with the internally threaded coupling54, as indicated at 51, and said coupling stud is formed in its upperend with a threaded socket 58 to receive the externally-threaded bearing49 in threaded engagement therewith, as indicated at 59, whereby theplate 22 is detachably secured to the yoke 55 and the speedometer casing40 is detachably secured to said yoke upon said plate. A look nut 50 isthreaded on the threaded stud 56 for engaging the lower end of thecoupling 54 for locking said stud in different positions in threadedengagement with said coupling. A bearing 6| is formed on the upperconnect ng member 62 of the yoke 55, through which bearing the driveshaft 41 of the speedometer |3 extends and in which hearing the lowerportion of said shaft is journaled. On the lower ends of the dependingyoke arms 63 are formed bearings 64, respectively, through whichbearings the axle 3 extends and in which bearings said axle isjournaled. On the axle 3 between the yoke bearings 64 is secured abeveled pinion 65 in mesh with the beveled pinion 48 on the lower end ofthe speedometer shaft 41, whereby said speedometer shaft and magnet disk46 are driven from the axle 3 for operating the speedometer I3. Theindicator arm 42 may be held stationary in position pointing to anygraduation 5| on the speedometer dial 4|, by means of a spring brake 66,one end of which is secured to the side wall of the speedometer casing40 at 61 and its other end is formed with a shoe 68 for engaging theupper surface of the iron disk 44 to hold said disk, indicator shaft 43and indicator arm 42 against rotation. The brake 66 is formed with adepending lug 69 to be engaged by a brakereleasing device 19, forreleasing the brake from the iron disc 44. Said brake-releasing device10 may be in the form of a solenoid 1|, comprising a coil 12, mounted onthe outside of the side wall of the speedometer casing 40, and a steelcore 13 extending from said coil through said casing wall into saidcasing, said core being formed at its inner end with a cam surface 14for engaging the brake lug 69 for releasing the brake 66 from the irondisk 44, and there being a plunger 15 of nonmagnetic material, such asbrass, extending into said coil 12 and secured at its inner end by ascrew connection 15' to the inner end of the core 13. By means of saidplunger 15 the core 13 may be pushed inwardly until its cam surface 14engages the brake lug 69 and releases the brake 66 from the iron disk44. The outer end of the plunger 15 may be formed with a knob 16. Ahousing 11 is placed over the speedometer l3 and the brake-releasingdevice 10 and is detachably secured in position to the plate 22, byscrews 18, extended through an external flange 19 forming the base ofsaid housing, there being an opening 88 in the upper wall of saidhousing through which the speedometer dial 4| and indicator arm 42 maybe seen for reading the speedometer. The side wall of the housing 11 hasan opening 8| through which extends the outer end portion of theactuating plunger 15 of the brake releasing device 19.

My brake-testing machine is controlled by an electrical circuit whichincludes a battery or generator 86 mounted in the body 2 of the trailerI; the stop solenoid 33 of the distance meas ing meter I2; the brakesetting solenoid 1| of the speedometer l3; and a switch 81, which isclamped upon the brake pedal 88 of the motor vehicle l9 whose brakes areto be tested by my brake-testing machine. The wiring of the circuit 85comprises a lead 89 extending from one pole of the generator or battery86 to one terminal of the coil 12 of solenoid 1|; a lead 99 extendingfrom the other terminal of said solenoid to one terminal 9| of theswitch 81; a lead 92 extending from lead 89 to one terminal of the coil34 of stop solenoid 33; a lead 93 extending from the other terminal ofsaid coil 34 to the lead and a lead 94 extending from the other terminal95 of said switch 81 to the other pole of the generator or battery 86.

The switch 81 comprises a base plate 96 of insulation to which issecured a clamp 91; a metal contact plate 98 secured to said base plate,and on the lower end of which is the terminal 95; a spring-metal contactplate, 99 on the lower end of which is the terminal 9|, and a smallspacing block I80 of insulation between the lower end portions of saidmetal contact plate 98 and said spring metal contact plate 99. Saidspacing block of insulation I08 is secured to said metal contact plate98 and said spring metal contact plate 99 is secured to said block ofinsulation, so that the forward portions of said contact plates arenormally spaced apart and the switch 81 is thus normally maintainedopen. The base plate of insulation 96 is clamped upon the brake pedal 88by the clamp 91, whereby the switch 86 is clamped in position on saidbrake pedal to be closed by the foot of the driver of the motor vehiclewhen he places his foot on the brake pedal 08 and depresses said pedalto apply the brakes of the motor vehicle.

The operation of my invention is as follows:

Normally the switch 01 is held open by the spring action of the springcontact 09 as shown in Fig. 8; the pin 35 of stop 32 is held projectedupwardly by the spring 37 adjacent the graduation 24 indicating zero onthe dial III, in the path of movement of the indicator arm I of thedistance measuring meter I2, as shown in Fig. 5; and the core I3 of thesolenoid I0 of the brake-releasing device of the speedometer I3 isprojected inwardly so that the cam surface I4 of said core engages thebrake lug 69 and holds the brake shoe 08 out of engagement with the irondisk 44, releasing said disk and the indicating arm of the speedometer,as shown in Fig. 7.

When it is desired to test the brakes of an automobile the forward endof the tongue 5 of the trailer I is first clamped to the rear bumper 9or any suitable part of a vehicle by the clamp I, as illustrated in Fig.1 of the drawings. The automobile is then driven until it reaches thespeed at which its brakes are to be tested, and the railer I is drawn atthe same speed by the automobile. The speedometer I3 is operated by therotating' axle 3 of the trailer I, through the medium of beveled pinions65 and 48, speedometer drive shaft 41, magnetic disk 46, iron disk 04,indicator shaft 43 and indicator arm 42 and said indicator arm points tothe graduation 5| on the speedometer dial 4| indicating the miles perhour at which the automobile is traveling. During said operation theindicator shaft I6 and its stud 28, of the distance measuring meter I2,are rotated by the axle 3 of the trailer I, through the medium of pinion2I, gear 20, shaft I9, worm I8 and worm gear II, but the indicator armI5 is held stationary against rotation, pointing to the zero graduation24 on the dial I4, by the stop 32, the stud 28 turning in the opening 29in said indicator arm I5, and the flange 21 and washer 30 turning infrictional contact against opposite sides respectively of said indicatorarm. When the automobile has reached the speed at which its brakes areto be tested, as aforesaid, the driver of the automobile places his footon the brake pedal 88 and depresses said pedal to the limit of itsmovement, during which operation the drivers foot depresses the springcontact 99 against the contact 98 of the switch 96, and closes saidswitch and the circuit 85. Electric current then passes from thegenerator or battery 86 through lead 89, coil 12 of solenoid II, lead 90to switch terminal SI, of switch 81, and from lead 89 current passesthrough lead 92, coil 34 of solenoid 33, lead 93 and lead 90 to switchter- 'minal BI, through switch 81 and its terminal 95 and through lead94 to the other pole of the generator or battery 80. The coils I2 and 30of the solenoids II and 33 respectively, being energized by the closingof the circuit, the core I3 is drawn into the coil I2 of solenoid II,and the core 35 is drawn into the coil 34 of the solenoid 33. As thecore I3 is drawn into the coil "I2 the cam surface Id of said core iswithdrawn from under the brake lug 69 and the brake 66 springs againstthe iron disk 44 of the speedometer I3 and holds said disk, indicatorshaft 43 and indicator arm 02 stationary, with said indicator armpointing to the speedometer graduation 5i indicating the miles per hourat which the automobile was traveling when the driver of the automobiledepressed the brake pedal 08. As the core is drawn into the coil 34 ofthe stop solenoid 33 said core is drawn below the indicator arm I5 ofthe distance measuring meter I2 and thereby releases said indicator arm,whereupon the frictional engagement of said arm by the flange 21 and thewasher 30 causes the indicator shaft I0 and its stud 23 to rotate saidindicator arm, until the automobile is brought to a stop by its brhkes,with said indicator arm pointing to the graduation 24 on the dial itindicating the distance which the automobile traveled while beingbrought to a stop by its brakes. Thus the number of feet in which anautomobile traveling at a given speed may be brought to a stop by itsbrakes is indicated by the distance measuring meter I2 and speedometerI3 of my brake testing machine.

The modification of the speedometer brake shown in Fig. 9 of thedrawings includes a solenoid IIII, a brake plunger I 02 of non-magneticmaterial, such as brass, and a plunger spring I03, the coil I04 of saidsolenoid being mounted on the outside of the speedometer casing ll!) between said casing and the housing TI. and the core I05 of said solenoidextending outwardly beyond the side wall of said housing through anopening I05 in said side wall. The brake plunger I02 extends through anopening IIll in the side wall of the speedometer casing into thesolenoid coil I04 and the inner end of said plunger is secured to theinner end of the solenoid core I05 by a screw connection I08. The outerend of the brake plunger I02 extends into the speedometer casing 40 andis formed with a brake shoe I09, which rests opposite the periphery ofthe speedometer iron disk 44, while the plunger spring I03 is coiledaround said brake plunger between the side wall of the speedometercasing 40 and said brake shoe I09 and urges said plunger forwardly andsaid shoe towards the periphery of said iron disk. A knob H0 is formedon the outer end of the solenoid core I05 and a spring latch III.secured at one end to the outside of the side wall of the housing I'I,normally engages at its other end the rear edge of said knob III] andholds said core and brake plunger I02 against the tension of spring I03,in position with the plunger brake shoe I09 withdrawn and released fromthe periphery of said iron disk 00. The sole noid coil I00 is includedin the brake-testing circuit 85 in the place of the solenoid coil I2,and upon depression of the brake pedal 88 and closing of the switch 8!the solenoid I0! is energized and the core I05 is drawn into the coilI00 of said solenoid, the core knob IIIJ escaping the spring latch III,while the plunger I02 is correspondingly moved by said core until theplunger brake shoe I09 engages the periphery of the iron disk 44 andbrakes the speedometer I3, holding the speedometer indicator arm 02pointing to the graduation 5| indicating the speed at which the vehiclewas traveling when the brake pedal 88 was depressed. The spring I03holds the plunger I02 and core I05 in braking position with the brakeshoe I09 against the periphery of the iron disk 40, when the brake pedal88 is released and the switch 81 springs open so that the circuit isbroken and the solenoid IN is deenergized. The brake continues to brakethe speedometer and hold the indicator arm 42 pointing to said speedgraduation 5|, as aforesaid, until the knob I III of the solenoid coreI05 is grasped by the operator and the solenoid core I 05 and brakeplunger I02 are pulled outwardly and the brake shoe I09 is therebyreleased from the periphery of the iron disk 44 and held in releasedposition by the engagement of the spring latch III with the inner sideof said knob H0, whereupon the speedometer is free to operate normally.

I do not limit my invention to the exact construction herein disclosed,since various changes may be made therein without departing from thespirit of the invention.

I claim:

1. A machine for testing automotivebrakes including a trailer, means forconnecting said trailer to an automobile, a speedometer mounted uponsaid trailer, said speedometer including a drive shaft, means wherebysaid drive shaft is driven by said trailer, a magnetic disc on saiddrive shaft, an indicator shaft, an iron disc on said indicator shaftadjacent said magnetic disc, an indicator arm on said indicator shaft. adial on which are speed graduations to which said indicator arm isadapted to point, and a spring for normally holding said indicator armin position pointing to the zero speed graduation on said dial, a springbrake for said iron disc, a solenoid including a coil, a core formedwith a cam sur- -face, and means for projecting said core beyond saidcoil so that its cam surface will engage said brake and release it fromsaid iron disc, a distance measuring meter mounted upon and to beoperated by said trailer, 2. stop for normally arresting the indicatorarm of said meter in its zero position, an electrical circuit includinga generator, said solenoid, a switch on the brake pedal of theautomobile to which said trailer is connected, which switch is closed bypressure of ones foot when applied to said brake pedal to depress thesame to close said circuit, whereby the core of said solenoid iswithdrawn from said brake to enable said brake to spring against saidiron disc to arrest the indicator arm of said speedometer, and meansactuated by said circuit, when closed by said switch, for withdrawingsaid stop from the indicator arm of said distance measuring meter toenable said trailer to drive said meter until the automobile is broughtto a stop by its brakes upon depression of said brake pedal.

2. A machine for testing automobile brakes including a trailer, meansfor connecting said trailer to an automobile, a speedometer mounted uponand operated by said trailer, a brake for said speedometer, abrake-releasing device for normally releasing said brake from thespeedometer to enable said trailer to operate said speedometer,

a distance measuring meter mounted upon said trailer, said distancemeasuring meter including an indicator shaft, means whereby said shaftis driven by said trailer, an indicator arm turnably mounted on saidindicator shaft, frictional means for holding said indicator arm againstturning on said shaft, a dial on said meter with graduations indicatingfeet, a stop on said meter for normally arresting said indicator armpointing to the zero graduation on said dial, an electrical circuitincluding a battery, a switch on the brake pedal of the automobile towhich said trailer is connected, which switch is closed by ones footwhen applied to said brake pedal to depress the same, means actuated bysaid circuit, when closed by said switch, for withdrawing said brakereleasing device from said speedometer brake to enable said brake toapply itself to said speedometer to arrest the speedometer indicatingarm, and means actuated by'said circuit, when closed by said switch, forwithdrawing said stop from said indicator arm of said distance-measuringmeter to enable said indicator shaft to rotate said indicator arm oversaid dial until the automobile is brought to a stop by its brakes,

3. In a machine for testing automotive brakes including a. trailer,means for connecting said trailer to an automobile, a speedometermounted upon said trailer, said speedometer including a drive shaft,means whereby said drive shaft is driven by said trailer, a magneticdisc on said drive shaft, an indicator shaft, an iron disc on saidindicator shaft adjacent said magnetic disc, an indicator arm on saidindicator shaft, a dial on which are speed graduations to which saidindicator arm is adapted to point, and a spring for normally holdingsaid indicator arm in position pointing to the zero speed graduation onsaid dial, a brake for said iron disk including a solenoid with a coiland a core, a brake plunger connected to the core of said solenoid andextending toward the periphery of said iron disk, a brake-testingelectrical circuit including a battery, the coil of said solenoid, and aswitch on the brake pedal of the vehicle to which said trailer isconnected, which switch is closed by the pressure of ones foot whenapplied to said brake pedal to depress the same to close said circuit,whereby the core of said solenoid is drawn into the coil of saidsolenoid and said brake plunger is forced against the periphery of saidiron disk to arrest the indicator arm of said speedometer.

FRANK L. HETZEL.

